1. Field of the Invention
The present invention relates generally to an intake air flow rate control system for an internal combustion engine of an automotive vehicle. More specifically, the present invention relates to a means for determining feedback control condition of the engine in a microcomputer implemented air flow rate control system.
2. Description of the Prior Art
In recent years, pollution of the atmosphere by nitrogen oxides NO.sub.x, carbon monoxide CO, gaseous sulfurous acid and so on produced in the exhaust gas of automotive vehicles has become a serious social problem. In addition to this, the price of fuel, i.e. gasoline or petrol, for automotive vehicles has become higher and higher, because of the limited resources thereof. For preventing atmospheries pollution caused by exhaust gas of vehicles and for using fuel economically, it has become necessary for current automotive vehicles to control engine speed accurately even when the vehicle engine is idling.